U.S. military officials say the body of a young male stowaway was found in the wheel well of an Air Force cargo jet that had landed in Germany after a routine mission in Africa.

Pentagon press secretary Navy Rear Admiral John Kirby told reporters Tuesday that the boy's body was found Sunday during a routine post-flight inspection of the aircraft when it landed at Ramstein Air Base. Kirby said the stowaway was a black male who may have been of African origin.

The plane was on a routine mission in Africa and had made stops in Senegal, Mali, Chad, Tunisia and Naval Air Station Sigonella in Sicily, before arriving at Ramstein.

As concerns swell over an outbreak of the deadly Ebola disease in several African countries, the military also confirmed that the body was tested for communicable diseases. Those tests came up negative.

“The cause of death, as well as the other circumstances surrounding this incident, remains under investigation,” Kirby said, adding the body had been taken to a German facility for an autopsy.

A stowaway aboard a military plane is a significant security breach, but Kirby said he had no information about how well-guarded the plane was during the Africa stops or how the boy managed to get into the compartment.

Kirby said the cause of death has not yet been determined.

In April, a Somali immigrant survived a flight from San Jose International Airport, California to Hawaii, while stowed away in the wheel well of a Boeing 767 commercial airliner.